Holding apparatus, transferring apparatus, image taking system, and image taking method

ABSTRACT

A holding apparatus including a suction nozzle which applies a negative pressure to a back surface of an object and thereby holds the object, a front-surface lighting device which emits a first visible light toward a front surface of the object held by the suction nozzle and thereby lights the front surface, and a back-surface lighting device which lights the back surface of the object held by the suction nozzle and which includes a light emitting plate which is provided around a base portion of the suction nozzle and emits a second light from a light emitting surface thereof facing a side of a free end of the suction nozzle that holds the object; and a dark infrared-ray transmitting filter which is dark, covers the light emitting surface of the light emitting plate, and transmits infrared rays of the second light.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a holding apparatus of r holding anobject such as an electric component (e.g., an electronic component), atransferring apparatus including the holding apparatus, and an imagetaking system and an image taking method each for taking an image of anobject held by a holding device, and relates particularly to the art oflighting an object.

2. Related Art Statement

The above-indicated holding apparatus , a transferring apparatus, animage taking system, and an image taking method are employed by, e.g. ,an electric-component mounting system which mounts an electric componenton a printed circuit board (“PCB”). In the electric-component mountingsystem, the holding apparatus receives an electric component from anelectric-component supplying device and mounts the component at apredetermined position on the PCB. Even if the current X-direction andY-direction positions of the component held by the holding apparatus aredeviated from respective reference positions, the component can beaccurately mounted at the predetermined position on the PCB, by movingthe holding apparatus to a corrected or modified position deviated fromthe predetermined position by respective distances between theX-direction and Y-direction positions of the component and thecorresponding reference positions. To this end, it is needed to measurethe respective distances between the X-direction and Y-directionpositions of the component held by the holding apparatus and thecorresponding reference positions. In addition, in some cases, it isneeded to read characters and/or a bar code affixed to the component andjudge of what sort the component is based on the read characters and/orbar code. To these ends, it is widely practiced that an image takingdevice takes an image of the component. Depending upon respective shapesof different sorts of electric components and/or different purposes ofimage taking, a silhouette image of each component is preferably neededin some cases, and a front-surface image of each component is preferablyneeded in other cases. To take a silhouette image of an electriccomponent held by the holding apparatus, it is needed to light a backsurface of the component that is held by the holding apparatus. To takea front-surface image of the component held by the holding apparatus, itis needed to light a front surface of the component that is opposed tothe image taking device.

There is a holding apparatus which includes a suction nozzle for suckingand holding an electric component; a front-surface lighting device whichlights a front surface of the component held by the nozzle; and aback-surface lighting device which lights a back surface of thecomponent. With this holding apparatus, an image taking device canselectively take a silhouette image or a front-surface image of thecomponent. Thus, the holding apparatus can be widely used. However, thelight emitting surface of the back-surface lighting device isconsiderably light and, if the image taking device takes a front-surfaceimage of the component in the background defined by the light emittingsurface while the front-surface lighting device lights the front surfaceof the component, the image taking device takes, in addition to thefront-surface image of the component, a light image of the background.In this case, it is difficult to extract accurately the image of theobject from the background, and incorrect results may be obtained by theprocessing of the extracted image of the object. This problem might besolved by moving the back-surface lighting device away from the objectwhen the front-surface image of the object is taken. In the latter case,however, the holding apparatus needs a more complicated structure, whichleads to another problem that the production cost of the holdingapparatus increases. In a particular case where the taking offront-surface image and the taking of silhouette image are frequentlyswitched with each other, it needs a long time to switch them, whichleads to lowering the operating efficiency of the holding apparatus.

In addition, it has widely been practiced that the suction nozzle and amain portion of the back-surface lighting device are constructed as anintegral unit. For example, a light emitting plate including a pluralityof point light sources, such as light emitting diodes, and a diffusinglayer for diffusing the lights emitted by the point light sources andthereby emitting a substantially uniform light, is fixed to the suctionnozzle, or alternatively a light emitting plate which absorbs infraredrays externally incident thereto and emits a visible light, a reflectingplate which reflects a light externally incident thereto, or a diffusingblock which diffuses a light externally incident thereto and emits alight toward the suction nozzle, is fixed to the suction nozzle.

However, if the main portion of the back-surface lighting device isprovided as the integral portion of the suction nozzle, the suctionnozzle costs high. Generally, the suction nozzle includes a suctionpipe, which may be bent to be not usable or whose suction surface (i.e.,free end surface) may be worn to be not usable. If the main portion ofthe back-surface lighting device is provided as the integral portion ofthe suction nozzle, the suction nozzle as a whole including the mainportion of the back-surface lighting device must be replaced withanother suction nozzle including a main portion of another back-surfacelighting device. This manner leads to increasing the running cost of theelectric-component mounting system. Meanwhile, in the case where aplurality of sorts of suction nozzles are exchanged with one anothercorresponding to a plurality of sorts of electric components to be held,the number of suction nozzles employed increases. If each of thosesuction nozzles includes a main portion of a back-surface lightingdevice, the running cost costs very high. Moreover, in the case wherethe main portion of each back-surface lighting device includes a lightemitting source, the light emitting source must be supplied withelectric power. In the last case, when the suction nozzles arerepetitively exchanged with one another, the contact of anelectric-power supply circuit which supplies the electric power to thelight emitting source may be worn or damaged, or an electric noise maybe produced from the contact.

While the foregoing explanation relates to the holding apparatus, thetransferring apparatus, the image taking device, etc. which are for usewith electric components, objects to be held by the holding apparatusare not limited to the electric components. The above-explained problemsmay commonly occur to all holding apparatuses, all transferringapparatuses, all image taking devices, etc. that are for use withobjects whose images need to be taken to recognize each object by imageprocessing or to determine X-direction, Y-direction, and rotationpositions of each object, measure one or more dimensions of each object,etc.

SUMMARY OF THE INVENTION

The present invention provides a holding apparatus, a transferringapparatus, an image taking system, and an image taking method that haveone or more of the technical features that are described below inrespective paragraphs given parenthesized sequential numbers (1) to(15). Any technical feature which includes another technical featureshall do so by referring, at the beginning, to the parenthesizedsequential number given to that technical feature. Thus, two or more ofthe following technical features may be combined, if appropriate. Eachtechnical feature may be accompanied by a supplemental explanation, asneeded. However, the following technical features and the combinationsthereof are just examples to which the present invention is by no meanslimited.

(1) According to a first feature of the present invention, there isprovided a holding apparatus comprising a suction nozzle which applies anegative pressure to a back surface of an object and thereby holds theobject; a front-surface lighting device which emits a first visiblelight toward a front surface of the object held by the suction nozzleand thereby lights the front surface; and a back-surface lighting devicewhich lights the back surface of the object held by the suction nozzleand which includes (a) a light emitting plate which is provided around abase portion of the suction nozzle and emits a second light from a lightemitting surface thereof facing a side of a free end of the suctionnozzle that holds the object; and (b) a dark infrared-ray transmittingfilter which is dark, covers the light emitting surface of the lightemitting plate, and transmits infrared rays of the second light. Thedark infrared-ray transmitting filter may be black. In the presentholding apparatus, the light emitting surface of the light emittingplate of the back-surface lighting device is covered by the darkinfrared-ray transmitting filter. Accordingly, when the front-surfacelighting device lights the front surface of the object in taking afront-surface image of the object, the background of the object isdefined by the dark filter. If the background is light, an image takingdevice takes, in addition to the front-surface image of the object, alight image of the background, so that when the taken images areprocessed, it is difficult to extract accurately the image of the objectfrom that of the background. Since the present holding apparatusprovides the dark background, the image of the object can be accuratelyextracted from that of the background. Meanwhile, when a silhouetteimage of the object is taken, the light emitting plate of theback-surface lighting device emits a light and the infrared-raytransmitting filter absorbs a visible-ray component of the emitted lightand transmits infrared rays only. Therefore, with an image taking devicewhich is sensitive to the infrared rays, a silhouette image of theobject can be taken. Accordingly, the present holding apparatus allows auser or an operator to obtain selectively a silhouette image or afront-surface image of the object by just operating selectively theback-surface lighting device or the front-surface lighting device. Thus,the present holding apparatus enjoys much ease of use. In the case wherean image taking device which is sensitive to both the visible light andthe infrared rays is employed, the single image taking device can becommonly used to take both the silhouette and front-surface images ofthe object. This feature contributes to reducing the production cost ofthe holding apparatus.

(2) According to a second feature of the present invention that includesthe first feature (1), the light emitting plate comprises a plurality oflight emitting elements arranged along the light emitting surfacethereof, and a diffusing plate which covers the light emitting surfaceand which diffuses respective lights emitted by the light emittingelements and thereby emits a substantially uniform light. If a pluralityof light emitting elements are arranged along a plane, a light emittingplate can be obtained which has a light emitting surface defined by theplane. In this case, however, the distribution of light along the lightemitting plane cannot be uniform. In the present holding apparatus, thelight emitting plate is covered by the diffusing plate which diffusesthe light emitted by the light emitting surface, thereby reducing theuneven distribution of light and emitting a substantially uniform light.The diffusing plate and the infrared-ray transmitting filter may beprovided by respective layers which are superposed on each other, or maybe provided by a single layer which functions as both of them.

(3) According to a third feature of the present invention that includesthe first or second feature (1) or (2), the holding apparatus furthercomprises a support portion to which the suction nozzle is detachablyattached, the back-surface lighting device including a main portionwhich is separate from the suction nozzle and is supported by thesupport portion such that when the suction nozzle is detached from thesupport portion, the main portion remains supported by the supportportion. In the present holding apparatus, the suction nozzle can bedetached, as needed, from the support portion, while the main portion ofthe back-surface lighting device remains supported by the supportportion. For example, in the case where a plurality of sorts of suctionnozzles are exchanged with one another corresponding to a plurality ofsorts of objects to be held, the main portion of the single back-surfacelighting device may be commonly used with each selected one of thedifferent sorts of suction nozzles. This feature also contributes todecreasing the running cost of the holding apparatus. Moreover, even inthe case where the main portion of the back-surface lighting deviceincludes a light emitting source, the main portion need not be detachedfrom the support portion when the different sorts of suction nozzles areexchanged with one another. This feature solves the problems that thecontact of an electric-power supply circuit is worn or damaged and anelectric noise is produced from the contact. According to the presentinvention, a portion of the back-surface lighting device may be providedas an integral portion of the suction nozzle or each of the differentsorts of suction nozzles. In this case, the suction nozzle, or eachsuction nozzle, including the portion of back-surface lighting device isattached to, and detached from, the support portion of the holding head.Alternatively, the entirety of the back-surface lighting device may bedirectly supported by the support portion of the holding apparatus. Inthe last case, when the suction nozzle is detached from the supportportion, no portion of the back-surface lighting device is detached fromthe support portion.

(4) According to a fourth feature of the present invention that includesthe third feature (3), the main portion of the back-surface lightingdevice comprises a tubular lighting portion which emits, from an innersurface thereof, a first light; and an outer lighting portion whichextends outward from the tubular lighting portion and which emits, fromone surface thereof, a second light in a direction parallel to acenterline of the tubular lighting portion, and wherein the suctionnozzle comprises a light converting portion which is fitable in an innerspace of the tubular lighting portion and which converts the first lightemitted by the tubular lighting portion into a third light having thedirection parallel to the centerline of the tubular lighting portion;and a suction pipe which holds the object and which extends from one endof the light converting portion in the direction parallel to thecenterline of the tubular lighting portion, one end portion of thesuction nozzle that is opposite to the suction pipe being detachablyattached to the support portion. In the present holding apparatus, thesuction nozzle includes, in addition to the suction pipe, the lightconverting portion as a portion of the back-surface lighting device. Inthe state in which the suction nozzle is attached to the support portionof the holding apparatus, the light converting portion is positioned inthe inner space of the tubular lighting portion, and converts the lightemitted from the inner surface of the tubular lighting portion into alight having a direction parallel to the centerline of the tubularlighting portion. Thus, the back surface of the object held by thesuction pipe is lighted with a sufficient amount of light even in thevicinity of the pipe, and a clear silhouette image of the object can betaken by an image taking device. It is preferred that the inner surfaceof the tubular lighting portion has a circular cross section. However,the inner surface may have a square cross section or any otherappropriate shape. The fourth feature (4) may not be combined with thethird feature (3) wherein the suction nozzle can be detached from thesupport portion while the main portion of the back-surface lightingdevice still remains supported by the support portion. That is, aholding apparatus may employ the fourth feature (4), independent of thethird feature (3).

(5) According to a fifth feature of the present invention that includesthe fourth feature (4), at least one of the tubular lighting portion andthe outer lighting portion comprises a plurality of light emittingelements which emits respective lights and which are arranged on aplurality of lattice points, respectively; and a diffusing layer whichdiffuses the lights emitted by the light emitting elements and therebyemits a substantially uniform light. In the present holding apparatus,the light emitting elements need the supply of electric power. However,the light emitting elements can remain on the support portion when thesuction nozzle is detached from the support portion. Therefore, anelectric-power supply circuit which supplies the electric power to thelight emitting elements need not be provided with a contact that isfrequently connected and disconnected. Thus, the present holdingapparatus is free of the problems that the contact is damaged and anelectric noise is produced from the contact.

(6) According to a sixth feature of the present invention that includesthe fourth or fifth feature (4) or (5), the light converting portioncomprises a tapered reflecting surface which is coaxial with the suctionpipe and whose radius increases in a direction away from a free end ofthe suction pipe that holds the object. The tapered reflecting surfacecan easily deflect the light emitted radially inward from a cylindricalinner circumferential surface of the tubular lighting portion, to adirection substantially parallel to an axis line of the suction pipe.

(7) According to a seventh feature of the present invention thatincludes the fourth or fifth feature (4) or (5), the light convertingportion comprises a diffusing block which diffuses the first lightemitted by the tubular lighting portion and emits the third light froman outer surface thereof located on a side of the suction pipe. Thediffusing block receives, at the outer surface thereof, the lightemitted from the inner surface of the tubular lighting portion, anddiffuses therein the received light so that the block becomes lighter asa whole. Accordingly, a light is emitted toward the object held by thesuction pipe from a pipe-side surface of the diffusing block.

(8) According to an eighth feature of the present invention thatincludes any one of the fourth to seventh features (4) to (7), theholding apparatus further comprises a support rod which is supported bythe support portion such that the support rod is movable in a directionparallel to an axis line of the suction pipe; an attaching device whichattaches the suction nozzle to one end portion of the support rod suchthat the suction nozzle is detachable from the support rod; and asupport-rod moving device which moves the support rod in a directionparallel to an axis line thereof, thereby moving the light convertingportion of the suction nozzle relative to the tubular lighting portionin the direction parallel to the centerline thereof, so that the suctionpipe of the suction nozzle is advanceable and retractable in thedirection parallel to the axis line thereof. In the present holdingapparatus, the suction nozzle including the light converting portion andthe suction pipe is attached to the support portion via the support rod,and the support rod is moved, by the support rod moving device, relativeto the support portion in an axial direction of the rod, so that thesuction pipe is advanced and retracted in an axial direction thereof.The advancing and retracting movements of the suction pipe can beutilized for, e.g., causing the pipe to hold the object or mount theobject on a mount surface. For example, in the case where the object isan electric component, the suction pipe can be caused to take thecomponent from an electric-component supplying device and mount the sameon a PCB. In this case, since the main portion of the back-surfacelighting device need not be advanced or retracted with the suctionnozzle, the nozzle can be quickly advanced and retracted while beingprevented from producing vibration or noise. Thus, the present holdingapparatus can mount electric components with high efficiency. Inaddition, the main portion of the back-surface lighting device can beeffectively prevented from interfering with electric components whichhave already been mounted on the PCB, and the force with which thesuction nozzle contacts each electric component and/or the force withwhich the nozzle presses each component on the PCB can be accuratelycontrolled.

(9) According to a ninth feature of the present invention that includesany one of the fourth to eighth features (4) to (8), the main portion ofthe back-surface lighting device further comprises an auxiliary lightingportion which is opposed to a gap provided between the tubular lightingportion and the light converting portion and which emits a fourth lighttoward a side of the suction pipe via the gap. In the present holdingapparatus, the auxiliary lighting portion lights the gap providedbetween the tubular lighting portion and the outer lighting portion.Accordingly, the back surface of the object is lighted with a uniformlight and a clear silhouette image of the object can be obtained.

(10) According to a tenth feature of the present invention, there isprovided a transferring apparatus comprising a holding apparatusaccording to any one of the first to ninth features (1) to (9); a movingdevice which moves the suction nozzle and the back-surface lightingdevice of the holding apparatus in a direction perpendicular to an axisline of the suction nozzle; and an image taking device which is providedat a predetermined position in a range in which the moving device movesthe suction nozzle and the back-surface lighting device of the holdingapparatus, so that when the suction nozzle and the back-surface lightingdevice are positioned at the predetermined position, the image takingdevice is opposed to the suction nozzle and the back-surface lightingdevice and takes an image of the object held by the suction nozzle. Therange in which the holding apparatus is moved may be a one-dimensional,two-dimensional, or three-dimensional range. In the present transferringapparatus, the object is held by the holding apparatus, which in turn ismoved by the moving device, so that the holding apparatus is opposed tothe image taking device. Thus, a silhouette image of the object held bythe suction nozzle can be taken by the image taking device. Image datarepresenting the thus taken silhouette image may be processed toidentify the object, determine one or more positions of the object heldby the suction nozzle, and/or measure one or more dimensions of theobject. For example, in the case where the object is an electriccomponent, the holding apparatus receives the electric component from anelectric-component supplying device, transfers it, and mounts it on aPCB. Before the holding apparatus mounts the component on the PCB, theimage taking device takes an image of the component held by the suctionnozzle, and the taken image is processed to determine one or more sortsof positional errors of the component held by the nozzle. After thepositional errors of the component are corrected, the holding apparatusmounts the component on the PCB.

(11) According to an eleventh feature of the present invention thatincludes the tenth feature (10), the transferring apparatus furthercomprises a nozzle stocker which stocks at least one suction nozzle; anda nozzle-exchange control device which controls the moving device tomove the suction nozzle of the holding apparatus to a position where thesuction nozzle of the holding apparatus is opposed to the nozzlestocker, and causes the suction nozzle of the holding apparatus to beexchanged with the one suction nozzle stocked by the nozzle stocker. Inthe present transferring apparatus, the moving device for transferringthe object held by the suction nozzle is additionally used forautomatically exchanging the suction nozzles with each other. Thus, thetransferring apparatus capable of automatically exchanging the suctionnozzles can be produced at low cost.

(12) According to a twelfth feature of the present invention, there isprovided an image taking system comprising a front-surface lightingdevice which emits a first visible light toward a front surface of anobject whose back surface is held by a holding portion of a holdingdevice and thereby lights the front surface; a first image taking devicewhich is sensitive to the first visible light and takes an image of theobject being lighted by the front-surface lighting device; aback-surface lighting device which is provided in back of the objectheld by the holding portion of the holding device, which lights the backsurface of the object held by the holding portion, and which includes(a) a light emitting plate which emits a second light from a lightemitting surface thereof facing a side of the holding portion holdingthe back surface of the object; and (b) a dark infrared-ray transmittingfilter which is dark, covers the light emitting surface of the lightemitting plate, and transmits infrared rays of the second light; and asecond image taking device which is sensitive to the infrared rays andtakes an image of the object being lighted by the back-surface lightingdevice. The present image taking system can take an excellent silhouetteimage of the object while the back-surface lighting device lights withthe infrared rays the back surface of the object, and can take an easilyprocessable front-surface image of the object in a dark backgrounddefined by the infrared-ray transmitting filter of the back-surfacelighting device. Thus, the present image taking system can selectivelytake, with ease, an excellent silhouette image and an excellentfront-surface image of the object.

(13) According to a thirteenth feature of the present invention thatincludes the twelfth feature (12), the first and second image takingdevices is provided by a single image taking device which is sensitiveto both the first visible light and the infrared rays of the secondlight. In the present image taking system, the single image takingdevice can be commonly used to take a silhouette image formed by theinfrared rays and take a front-surface image formed by the visiblelight. This feature contributes to reducing the production cost of theimage taking system.

(14) According to a fourteenth feature of the present invention, thereis provided a method of taking an image of an object which is held by aholding device, comprising the steps of providing, in front of theobject whose back surface is held by a holding portion of the holdingdevice, a front-surface lighting device which emits a first visiblelight toward a front surface of the object and thereby lights the frontsurface, providing, in back of the object held by the holding portion ofthe holding device, a back-surface lighting device which lights the backsurface of the object held by the holding portion and which includes (a)a light emitting plate which emits a second light from a light emittingsurface thereof facing a side of the holding portion holding the backsurface of the object; and (b) a dark infrared-ray transmitting filterwhich is dark, covers the light emitting surface of the light emittingplate, and transmits infrared rays of the second light, operating thefront-surface lighting device and a first image taking device which issensitive to the first visible light, to take, in a background definedby the dark infrared-ray transmitting filter, an image of the frontsurface of the object that is lighted by the front-surface lightingdevice, and operating the back-surface lighting device and a secondimage taking device which is sensitive to the infrared rays of thesecond light, to take a silhouette image of the object whose backsurface is lighted by the back-surface lighting device. The presentimage taking method can enjoy the same advantages as those of the imagetaking system according to the twelfth feature (12).

(15) According to a fifteenth feature of the present invention thatincludes the fourteenth feature (14), the first and second image takingdevices is provided by a single image taking device which is sensitiveto both the first visible light and the infrared rays of the secondlight. The present image taking method can enjoy the same advantages asthose of the image taking system according to the thirteenth feature(13).

BRIEF DESCRIPTION OF THE DRAWINGS

The above and optional objects, features, and advantages of the presentinvention will be better understood by reading the following detaileddescription of the preferred embodiments of the invention whenconsidered in conjunction with the accompanying drawings, in which:

FIG. 1 is a schematic plan view of an electronic-component (“EC”)mounting system including a holding apparatus to which the presentinvention is applied;

FIG. 2 is a partly cross-sectioned, front elevation view of the holdingapparatus and an image taking device of the EC mounting system of FIG.1;

FIG. 3 is a cross-sectioned, front elevation view of a suction nozzle, aholder body, and a back-surface lighting device of the holding apparatusof FIG. 2;

FIG. 4 is a view for explaining the manner in which suction nozzles areexchanged with each other in the EC mounting system of FIG. 1;

FIG. 5 is a diagrammatic view of a relevant portion of a control deviceof the EC mounting system of FIG. 1; and

FIG. 6 is a schematic plan view corresponding to FIG. 1, showing anotherelectronic-component mounting system employing two CCD cameras.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter there will be described an electronic-component (“EC”)mounting system as a preferred embodiment of the present invention, byreference to FIGS. 1 to 5. The EC mounting system mounts an EC 32 (FIG.2) as a sort of electric component as an object, on a printed circuitboard (“PCB”) as a sort of circuit substrate.

In FIG. 1, reference numeral 10 designates a base on which an ECtransferring and mounting device 12, an EC supplying device 14, and aPCB conveying device 16 are provided. The PCB conveying device 16includes a PCB conveyor 18 which extends in an X direction, indicated atarrow in FIG. 1, and which conveys a PCB 20 to a predetermined EC-mountposition where the PCB 20 is positioned and supported by a PCBpositioning and supporting device (not shown).

The EC supplying device 14, indicated at two-dot chain line in FIG. 1,is provided on one side of the PCB conveyor 18 in a Y direction which isperpendicular to the X direction on a horizontal plane. The EC supplyingdevice 14 includes a number of EC-supply cartridges 22 which arearranged in the X direction, and is fixed at a predetermined position.

The EC transferring and mounting (“T/M”) device 12 includes an EC holder30 (FIG. 2) which is linearly movable in each of the X and Y directionsto receive the EC 32 from the EC supplying device 14, transfer the EC32, and mount the same 32 on the PCB 20. To this end, the EC T/M device12 additionally includes two ball screws 34 which are provided, on thebase 10, on both sides of the PCB conveyor 18 in the Y direction suchthat the two ball screws 34 extend parallel to each other. The two ballscrews 34 are threadedly engaged with two nuts (not shown),respectively, which are fixed to an X-direction slide 36. When the twoballs screws 34 are rotated by two X-direction servomotors 38,respectively, the X-direction slide 36 is moved in the X direction. Onthe base 10, there are provided two guide rails (not shown) as two guidemembers below the two ball screws 34, respectively. The X-directionslide 36 has two guide blocks (not shown) as two guided members whichslideably fit on the two guide rails, respectively, and cooperate withthe same to guide the movement of the slide 36 in the X direction.

The X-direction slide 36 supports a ball screw 40 (FIG. 2) which extendsin the Y direction, and a Y-direction slide 42 is threadedly engagedwith the hall screw 40 via a nut (not shown). When the the ball screw 40is rotated by a Y-direction servomotor 44, the Y-direction slide 42 ismoved in the Y direction while being guided by a pair of guide rails 46which extend in the Y direction.

The base 10, the nuts, the ball screws 34, the X-direction servomotors38, the X-direction slide 36, the nut, the ball screw 40, theY-direction servomotor 44, and the Y-direction slide 42 cooperate withone another to provide an X-Y robot 48.

As shown in FIG. 2, the EC holder 30 is attached to a vertical surface60 such that the EC holder 30 is movable up and down and is rotatableabout a vertical axis line. The vertical surface 60 additionallysupports an elevating and lowering device 62 which elevates and lowersthe EC holder 30, that is, moves the same 30 up and down; a rotatingdevice 64 which rotates the EC holder 30 about the vertical axis lineand thereby rotates the EC 32 held by the holder 30 about the same axisline; and a CCD (charge-coupled device) camera 66 (FIG. 1) which takesrespective images of reference marks affixed to the PCB 20.

The EC holder 30 includes a suction nozzle 68 which sucks and holds theEC 32; and a holder body 70 which supports the suction nozzle 68. Theholder body 70 includes a spline axis member 72 which fits in a splinehole of a sleeve 74. The sleeve 74 fits in an arm 78 projecting from thevertical surface 60 of the Y-direction slide 42, such that the sleeve 74is rotatable about the vertical axis line and is immovable in an axialdirection thereof. A lower end portion of the sleeve 78 that projectsdownward from the arm 78 supports a pair of wheels 80, 82 that preventbacklash. The two wheels 80, 82 are meshed with a wheel 88 which isfixed to an output shaft 86 of a rotation servomotor 84 of the rotatingdevice 64 and is rotated by the rotation servomotor 84. Thus, the splineaxis member 72 is accurately rotated about its axis line by theservomotor 84 via the wheels 88, 80, 82 and the sleeve 74, andaccordingly the EC holder 30 is accurately rotated about the verticalaxis line which coincides with the axis line of the spline member 72.The rotation servomotor 84 can rotate in opposite directions, and thecurrent rotation angle of the servomotor 84 is detected by an encoder 90as a sort of rotation-angle detector. Thus, the current rotation angleof the EC holder 30 is detected or obtained.

A connect member 100 is attached to an upper end portion of the splineaxis member 72, such that the connect member 100 is rotatable relativeto the spline member 72 and is immovable relative to the same 72 in itsaxial direction. The connect member 100 includes a horizontal portion102 which is fixed to a nut 106 which in turn is threadedly engaged witha ball screw 104. The ball screw 104 is attached to the vertical surface60 of the Y-direction slide 42 such that the ball screw 104 is rotatableabout its vertical axis line and is immovable in its axial direction.When the ball screw 104 is rotated by an elevating and loweringservomotor 114 via timing pulleys 108, 110 and a timing belt 112, thenut 106 is elevated and lowered, so that the connect member 100, theholder body 70, and the EC holder 30 are elevated and lowered, i.e.moved up and down.

The elevating and lowering servomotor 114 can rotate in oppositedirections, and the current rotation angle of the servomotor 114 isdetected by an encoder 116 as a sort of rotation-angle detector. Thus,the current height position of the EC holder 30 is detected or obtained.In the present embodiment, the EC holder 30 is elevated and lowered insucking (i.e., holding) and mounting the EC 32, in an EC-suck-and-mountrange under its downward-movement-start position (i.e., uppermost endposition) shown in FIG. 2. Each of the elevating and lowering servomotor114, the X-direction servomotors 38, and the Y-direction servomotor 44is an electric rotary motor as a sort of electric motor and isaccurately controllable with respect to rotation angle or phase androtation speed. Those servomotors 114, 38, 44 may be replaced withstepper motors.

The suction nozzle 68 is supported by a lower end portion of the splineaxis member 72. The suction nozzle 68 applies a negative pressure to aback surface of the EC 32 and thereby holds the same 32. The splinemember 72 has an inner passage 132 which is connected to a vacuum source(not shown) via a port 134. A solenoid-operated direction-control valve136 (FIG. 5) is provided between the passage 132 and the vacuum source.Upon switching of the direction-control valve 136, the suction nozzle 68is selectively communicated with the vacuum source or the atmosphere,and sucks or releases the EC 32.

As shown in FIGS. 2 and 3, the suction nozzle 68 is-attached to thespline axis member 72 via an adaptor 150 such that the suction nozzle 68is coaxial with the spline member 72. The adaptor 150 fits in areceiving hole 154 formed in a nozzle receiving portion 152 provided bythe lower end portion of the spline member 72, such that the adaptor 150is movable relative to the receiving portion 152 in the axial directionof the spline member 72. The adaptor 150 is held by a plurality ofholding members 156 (only one holding member 156 is shown in FIGS. 2 and3) which are supported by the nozzle receiving portion 152 such that theholding members 156 are equiangularly spaced from each other about theaxis line of the spline member 72. The adaptor 150 is biased by acompression coil spring 158 as a sort of spring member as an elasticmember as a biasing member or device, in a direction in which theadaptor 150 is moved or pushed downward out of the nozzle receivingportion 152.

The nozzle receiving portion 152 has a plurality of recesses 162 whichextend parallel to the axis line of the spline axis member 72 and whichare equiangularly spaced from each other about the axis line. Theholding members 156 fit in the recesses 162, respectively, such thateach of the holding members 156 is pivotable about a horizontal axisline, and are prevented from coming off the nozzle receiving portion 152by. a ring-like spring member 164 wound around the receiving portion152. Each holding member 156 has a projection 166 which projects towarda centerline of the nozzle receiving portion 152 and which fits in abottom recess 168 formed in the bottom of the receiving portion 152.Each holding member 156 is pivotable about its horizontal axis line atwhich the projection 166 contacts a bottom surface of the bottom recess168. The horizontal axis line is perpendicular to a lengthwise directionof the each holding member 156 and is parallel to a tangential linewhich contacts a portion of the receiving portion 152 to which the eachholding member 156 is attached.

Each of the holding members 156 has, above the projection 166, anoperable portion 170 which fits in an upper recess 172 formed in thenozzle receiving portion 152. Since each holding member 156 fits in therecess 162 and its operable portion 170 fits in the upper recess 172,the each holding member 156 is prevented from being rotated or pivotedabout a horizontal axis line perpendicular to the axis line of thespline axis member 72.

A lower end portion of each of the holding members 156 fits in a lowerrecess 176 formed in a large-diameter portion 174 of the adaptor 150.Thus, the adaptor 150 is prevented from being rotated relative to thenozzle receiving portion 152. The lower end portion of the each holdingmember 156 has an engaging projection 178 which projects toward theadaptor 150. Since the respective engaging projections 178 of theholding members 156 engage a lower surface of the large-diameter portion174 of the adaptor 150, the adaptor 150 is prevented from coming off thereceiving hole 154 of the nozzle receiving portion 152. When the adaptor150 is removed from the nozzle receiving portion 152, first, the splineaxis member 72 is moved downward from its downward-movement-startposition, and then the respective operable portions 170 of the holdingmembers 156 are pushed to pivot the holding members 156 against thebiasing force of the spring member 164. Thus, the engaging projections178 of the holding members 156 are released from the engagement with thelarge-diameter portion 174 of the adaptor 150, so that the adaptor 150can be removed from the receiving portion 152. The adaptor 150 has alower end surface providing a plane contact surface 180 perpendicular tothe axis line of the spline axis member 72.

The suction nozzle 68 includes a suction pipe 192 and a suction-pipeholder 190 which is formed of a synthetic resin and which holds thesuction pipe 192 such that the pipe 192 is coaxial therewith. An endportion of the pipe holder 190 that is distant from the suction pipe 192provides a fitting portion 194 which fits in a receiving hole 196 formedin the adaptor 150 and which is prevented from coming off the adaptor150 by a spring member 204. The pipe holder 190 has a stepped,cylindrical shape whose diameter stepwise decreases in an upwarddirection, and has a stepped, plane contact surface 198 perpendicular tothe center line of the holder 190. An upper end portion of the fittingportion 194 has a tapered surface 200 whose diameter decreases in anupward direction. The spring member 204 has a generally U shapedconfiguration whose two arms fit in two recesses 206, respectively,formed in the adaptor 150, such that respective intermediate portions ofthe two arms project, owing to the elastic restoring force of the springmember 204, radially inwardly of the inner circumferential surface ofthe receiving hole 196 of the adaptor 150. Since the two arms of thespring member 204 are bent so that respective free end portions of thetwo arms approach each other, the spring member 204 is prevented fromcoming off the adaptor 150.

When the fitting portion 194 of the suction-pipe holder 190 is insertedinto the receiving hole 196 of the adaptor 150 while the tapered surface200 of the fitting portion 194 widens the two arms of the spring member204, the two arms of the spring member 204 fit in an annular groove 210formed in the fitting portion 194 and thereby engage the fitting portion194. Thus, the spring member 204 holds the pipe holder 190 and somewhatdraws or pulls the same 190 into the receiving hole 196 of the adaptor150. The fitting portion 194 fits in the receiving hole 196 such thatthe contact surface 198 of the pipe holder 190 is held in contact withthe contact surface 180 of the adaptor 150, and in this state the centerof the circular cross section of the spring member 204 is somewhat lowerthan that of the semicircular cross section of the annular groove 210.Therefore, the spring member 204 engages the upper portion of the innersurface of the annular groove 210, thereby drawing or pulling, owing toits elastic restoring force, the pipe holder 190 into the receiving hole196. Since the two contact surfaces 198, 180 are held in contact witheach other, the suction nozzle 68 is positioned in a vertical directionand is prevented from being tilted relative to the spline axis member72. The suction nozzle 68 can be removed from the adaptor 150 by pullingthe nozzle 68 with a force greater than the pulling force of the springmember 204, in a direction opposite to the direction in which the springmember 204 pulls in the nozzle 68. In the present embodiment, the splineaxis member 72 cooperates with the adaptor 150 to provide a support rodwhich supports the suction nozzle 68 such that the nozzle 68 isdetachable from the support rod. The spring member 204 as the means forattaching the suction nozzle 68 to the support rod such that the nozzle68 is detachable from the rod, may be replaced with a device whichattaches, owing to a negative pressure or a magnetic force, the nozzle68 to the rod such that the nozzle 68 is detachable from the rod.

The suction-pipe holder 190 includes a block portion 220 which isopposite to the fitting portion 194 and which has a cylindrical shapewhose diameter is greater than that of the fitting portion 194. Theblock portion 220 includes an upper portion 222 and a lower portion 224which are provided as separate members for easier production and areassembled with each other. The upper portion 222 is formed integrallywith the fitting portion 194, and the suction pipe 192 is attached tothe lower portion 224 such that the pipe 192 extends downward from alower surface 226 thereof along a straight line extending downward fromthe centerline of the pipe holder 190. The upper portion 222 has a lowertapered surface 228 which is coxial with the suction pipe 192 and isinclined by 45 degrees relative to the centerline of the pipe holder 190and whose diameter increases in a direction away from the suction pipe192. The lower portion 224 has an upper tapered surface 230corresponding to the lower tapered surface 228 of the upper portion 222.The upper and lower portions 222, 224 are connected to each other at therespective tapered surfaces 228, 230 via a tapered reflecting surface232 corresponding to the tapered surfaces 228, 290. In the presentembodiment, a metallic layer 234 such as aluminum or silver is formedby, e.g., vapor deposition on the lower tapered surface 228 of the upperportion 222, and the reflecting surface 232 is defined or provided by alower surface of the metallic layer 234. However, it is possible to formthe reflecting surface 232 by forming a metallic layer on the uppertapered surface 230 of the lower portion 224, or it is possible toemploy silver mirror reaction in place of vapor deposition. Moreover, itis possible to employ an upper portion 222 formed of metal and polish alower tapered surface 228 of the upper portion 222 into a taperedreflecting surface 232. The lower portion 224 of the block portion 2220is formed of a transparent synthetic resin, and the lower surface 226 ofthe lower portion 224 is covered with a dark (e.g., black infrared-ray(“IR-ray”) transmitting filter 240. The IR-ray transmitting filter 240includes an IR-ray transmitting layer and a diffusing layer which aresuperimposed or laminated on each other. The IR-ray transmitting filter240 absorbs visible rays and transmits and diffuses IR rays. Thus, theIR-ray transmitting filter 240 also functions as a diffusing plate.

A main lighting portion 248 is supported by the vertical surface 60 ofthe Y-direction slide 42, such that the main lighting portion 248 iscoaxial with the suction nozzle 68 and surrounds the same 68 positionedat its downward-movement-start position. The main lighting portion 248cooperates with the block portion 220 and an auxiliary lighting portion290 to provide a back-surface lighting device 250. The main lightingportion 248 includes a cylindrical lighting portion 252 (hereinafter,referred to as the “tubular” lighting portion 252), and a flange-likelighting portion 254 which extends radially outwardly from a lower endof the tubular lighting portion 252 and has an annular-flange-likeshape. The flange-like lighting portion 254 is fixed to the verticalsurface 60 of the Y-direction slide 42 via a bracket (not shown). Asmall gap is provided between the suction-pipe holder 190 and the twolighting portions 252, 254. The suction nozzle 68 is movable relative tothe main lighting portion 248 in an axial direction of the nozzle 68. InFIG. 3, the gap provided between the pipe holder 190 and the mainlighting portion 248 is exaggerated for easier understanding purposesonly.

The tubular lighting portion 252 includes a light emitting body 258which includes a disc-like PCB and a number of light emitting diodesarranged on lattice points on the PCB. One surface of the PCB that doesnot support the diodes is supported by a cylindrical support member 260,so that a light emitting surface 262 of the lighting portion 252 facesradially inward. Since the PCB and the diodes are well known in the art,the description and illustration thereof are omitted. The cylindricalsupport member 260 is connected to a drive circuit 406 (FIG. 5,described later) via a lead wire (not shown). When the drive circuit 406supplies an electric current to the light emitting body 258, the tubularlighting portion 252 emits a light from the light emitting surface 262,i.e., the inner circumferential surface thereof, toward the suctionnozzle 68. The diodes of the light emitting body 258 are ones each ofwhich emits a light including a plenty of IR rays.

When the light is emitted from the light emitting surface 262 of thetubular lighting portion 252, toward the suction-pipe holder 190 of thesuction nozzle 68, in a direction perpendicular to the axis line of thenozzle 68, the light is reflected by the reflecting surface 232 of thepipe holder 190 and thereby is deflected to a downward direction. Thelight passes through the lower portion 224 of the block portion 220, andthe components thereof other than the IR rays are removed, and the IRrays are diffused, by an IR-ray transmitting filter 240. Consequentlythe back surface of the EC 32 held by the suction pipe 192 is lightedwith the substantially uniform IR rays only.

Like the tubular lighting portion 252, the flange-like lighting portion254 includes a light emitting body 270 which includes a disc-like PCBand a number of light emitting diodes arranged in a lattice or a matrixon the PCB. One surface of the PCB that does not support the diodes issupported by an annular support member 272, so that a light emittingsurface 274 of the lighting portion 270 faces downward, i.e., toward thesuction pipe 192. The light emitting surface 274, i.e., the lowersurface of the light emitting body 270 is covered with an annular,IR-ray transmitting filter 278. Since the light emitting body 270 andthe transmitting filter 278 are similar to the light emitting body 258and the transmitting filter 240, respectively, substantially uniform IRrays are emitted downward from the surface 274, so that the back surfaceof the EC 32 held by the suction pipe 192 is lighted with thesubstantially uniform IR rays. In the present embodiment, theflange-like lighting portion 254 is driven by the same drive circuit 406as that for the tubular lighting portion 252. However, it is possible toemploy two drive circuits for driving the two lighting portions 252,254, respectively.

An auxiliary lighting portion 290 is provided above the tubular lightingportion 252 such that the auxiliary lighting portion 290 is opposed tothe gap provided between the tubular lighting portion 252 and thesuction-pipe holder 190. The auxiliary lighting portion 290 is fixed tothe vertical surface 60 of the Y-direction slide 42 via a bracket (notshown). The auxiliary lighting portion 290 includes a light emittingbody 294 which is supported by an annular support plate 292 and whoselower surface, i.e., light emitting surface 296 is covered with anannular IR-transmitting filter 300 like the flange-like lighting portion254. Since the light emitting body 294 and the transmitting filter 300are similar to the light emitting body 258 and the transmitting filter240, respectively, the auxiliary lighting portion 290 emits onlysubstantially uniform IR rays which are directed toward the suction pipe192 via the gap provided between the pipe holder 190 and the tubularlighting portion 252.

A CCD camera 310 as an image taking device which takes an image of theEC 32 held by the suction nozzle 68 is provided on the base 10 at aposition between the EC supplying device 14 and the PCB conveying device16 in the Y direction. The CCD camera 310 includes a lens system and amatrix of CCDs, and is opposed, in the state in which the EC holder 30is positioned at an EC-image-take position where the suction pipe 192 ispositioned right above the CCD camera 310, to the back-surface lightingdevice 250 with the EC 32 held by the suction pipe 192 being positionedbetween the camera 310 and the lighting device 250. A ring lamp 320 isprovided around the CCD camera 310, and is fixed to the base 10 via abracket (not shown). The ring lamp 320 emits a visible light toward afront surface of the EC 32 held by the suction pipe 192, and thusfunctions as a front-surface lighting device. In the present embodiment,the CCD camera 310 is sensitive to each of the visible light and the IRrays.

However, the single CCD camera 310 may be replaced with two CCD cameras310A, 310B that provided, on the base 10, at respective differentpositions between the EC supplying device 14 and the PCB conveyingdevice 16 in the Y direction, shown in FIG. 6. In this case, the ringlamp 320, not shown in FIG. 6, is provided around the CCD camera 310Aonly, and is fixed to the base 10.

In addition, a nozzle stocker 330 is provided on the base 10 at aposition between the EC supplying device 14 and the PCB conveying device16 in the Y direction. In the present embodiment, the nozzle stocker 330has the same construction as that of the nozzle stocker disclosed inU.S. patent application Ser. No. 09/234,489. Accordingly, the detaileddescription and illustration of the nozzle stocker 330 are omitted, andare briefly described below.

As shown in FIG. 4, the nozzle stocker 330 includes a generallyplate-like, nozzle holding member 332 and a preventing plate 334. Thenozzle stocker 330 stocks or stores a plurality of sorts of suctionnozzles 68 (only one nozzle 68 is shown in FIG. 4) including respectivesuction pipes 192 having different diameters corresponding to differentshapes and/or dimensions of ECs 32. The nozzle holding member 332 has aplurality of stepped holding holes 340 (only one hole 340 is shown inFIG. 4) each of which receives one suction nozzle 68. Each holding hole340 includes a small-diameter portion 342 whose diameter allows asuction pipe 192 having the greatest diameter to fit therein; and alarge-diameter portion 344 whose diameter is somewhat greater than thatof the block portion 220 of the pipe holder 190.

The preventing plate 334 has a thin plate-like shape and covers theholding holes 340 of the nozzle holding member 332. The plate 334 has aplurality of circular holes 350 (only one hole 350 is shown in FIG. 4),and a plurality of connecting holes 352 each of which connects betweenadjacent two circular holes 350. Each of the circular holes 350 has adiameter somewhat greater than that of the large-diameter portion 344 ofeach nozzle holding hole 340. The circular holes 350 are formed at apitch equal to that at which the nozzle holding holes 340 are formed inthe nozzle holding member 332 in each of its lengthwise direction andits widthwise direction perpendicular to the lengthwise direction. Eachconnecting hole 352 has a width smaller than the diameter of the blockportion 220 of the pipe holder 190 of each suction nozzle 68. The widthof each connecting hole 352 is defined as a dimension thereof in adirection parallel to a widthwise direction of the preventing plate 334,on a plane parallel to the plane of the plate 334. A pair of projectionsof the preventing plate 334 that cooperate with each other to defineeach connecting hole 352 provide preventing portions 354 which preventeach suction nozzle 68 from coming off the nozzle holding member 332.Each pair of preventing portions 354 are distant from, and opposed to,each other in the widthwise direction of the preventing plate 354.

A preventing-plate moving device 360 (FIG. 5) moves the preventing plate324 relative to the nozzle holding member 332 in the lengthwisedirection of the plate 324 or the member 332, to an operative positionwhere the pairs of preventing portions 354 are positioned above thenozzle holding holes 340, respectively, and prevent the suction nozzles68 from coming off the holes 340, respectively, and to a retractedposition where the circular holes 350 are positioned right above theholding holes 340, respectively, and allow the nozzles 68 to be takenaway from the holes 340, respectively. The preventing-plate movingdevice 360 may include an air-pressure-operated cylinder device.

The present EC mounting system is controlled by a control device 370shown in FIG. 5. The control device 370 is essentially provided by acomputer 380 including a PU (processing unit) 372, a ROM (read onlymemory) 374, a RAM (random access memory) 376, and a bus 378 connectingthe elements 372, 374, 376 with one another. An input interface 382 isconnected to the bus 378, and the CCD cameras 66, 310, the encoders 90,116, and an input device 384 are connected to the input interface 382.The input device 384 includes a keyboard or an operation panel which isoperable by an operator. An output interface 386 is connected to the bus378 on one hand, and is connected to various drive circuits 400, 401,402, 403, 404, 405, 406, 407, 408 on the other hand. The PCB conveyor18, the X-direction servomotors 38, the Y-direction servomotor 44, therotation servomotor 84, the elevating and lowering servomotor 114, thesolenoid-operated direction-control device 136, the three lightingportions 252, 254, 290 (i.e., the tubular lighting portion 252, theflange-like lighting portion 254, the auxiliary lighting portion 290),the ring lamp 320, and the preventing-plate moving device 360 areconnected to the drive circuits 401 to 409, respectively. The ROM 374stores various control programs which are needed to suck (i.e., hold)and mount the EC 32.

In the EC mounting system constructed as described above, the suctionnozzle 68 receives the EC 32 from the EC supplying device 14 at theEC-receive position (i.e., the EC-suck position) and mounts the same 32on the PCB 20 at the EC-mount position. Between the EC-receive positionand the EC-mount position, the CCD camera 310 takes a silhouette imageor a front-surface image of the EC 32 held by the suction pipe 192. Thecontrol device 370 processes image data representing the takensilhouette or front-surface image of the EC 32 and determines thecurrent rotation position of the EC 32 and the X-direction andY-direction positional errors of the EC 32 held by the suction nozzle68. The control device 370 corrects the current rotation position of theEC 32 and the X-direction and Y-direction positional errors of the EC32, by rotating the suction nozzle 68 and stopping the EC holder 30 atcorrected X-direction and Y-direction positions. Then, the suctionnozzle 68 mounts the EC 32 on the PCB 20.

When the EC holder 30 receives an EC 32 from the EC supplying device 14,the X-direction slide 36 and/or the Y-direction slide 42 are moved toposition the suction pipe 192 at a position right above one of theEC-supply cartridges 22 that supplies the EC 32 to be received by the ECholder 30. Then, the elevating and lowering device 62 lowers the ECholder 30 from its downward-movement-start position, so that the suctionpipe 192 contacts the upper surface of the EC 32. Although the pipe 192is further lowered by a small distance after contacting the EC 32, thepipe 192 and the EC 32 are prevented from being broken because the pipe192 compresses the compression coil spring 158 and moves relative to thespline axis member 72. In this state, the suction pipe 192 iscommunicated with the vacuum source to suck and hold the EC 32.

Then, the EC holder 30 is elevated, and the X-Y robot 48 is operated toposition the suction pipe 192 at the image-take position right above theCCD camera 310, which takes a silhouette or a front-surface image of theEC 32 held by the pipe 192. For example, in the case where the EC 32 isof a flat-package type, as shown in FIG. 2, in which lead wires projectoutward from side surfaces of a main body, the control device 370chooses taking a silhouette image of the EC 32. When the CCD camera 310takes a silhouette image of the EC 32, the control device 370 turns onthe back-surface lighting device 250 and turns off the ring lamp 320.Thus, the IR rays emitted by the flange-like lighting portion 254 lightthe back surface of the EC 32, and the light emitted by the tubularlighting portion 252 is deflected to a downward direction by thereflecting surface 232 and then only IR rays are transmitted, and madesubstantially uniform, by the IR-ray transmitting filter 240, so thatthe IR rays light the back surface of the EC 32 in the vicinity of thesuction pipe 192. In addition, the auxiliary lighting portion 290 emitsIR rays toward the gap provided between the suction-pipe holder 190 andthe tubular lighting portion 252. Thus, the IR rays emitted by theback-surface lighting device 250 uniformly light the back surface of theEC 32 and its background, and thereby form a silhouette image of the EC32 on the imaging surface of the CCD camera 310, i.e., the matrix ofsolid-state imaging elements (i.e., the matrix of CCDs) of the same 310.Since the CCD camera 310 is sensitive to the IR rays, the camera 310takes a clear silhouette image of the EC 32 with a lighter background.

However, there are some cases where a silhouette image of the EC 32 heldby the suction pipe 192 does not provide sufficient information. Forexample, in the case of a PLCC type EC in which lead wires project fromside surfaces of a main body such that respective free end portions ofthe lead wires are curved like “J” and are located inside an outerperipheral edge of the main body, or in the case of a pin-grid-array(PGA) type EC in which lead wires perpendicularly project from grid orlattice points on a front surface of a main body, the control device 370chooses taking a front-surface image of the EC 32. As far as the presentinvention is concerned, the “front” surface of the EC 32 is defined as asurface opposed to the CCD camera 310, and the “back” surface of the EC32 is defined as a surface opposite to the “front” surface. When the PGAtype EC is mounted on the PCB 20, the “front” surface of the EC contactsthe PCB 20. When the CCD camera 310 takes a front-surface image of theEC 32, the control device 370 turns on the ring lamp 320 and turns offthe back-surface lighting device 250. Thus, the ring lamp 320 emits thevisible light toward the front surface of the EC 32 held by the suctionpipe 192, and the light reflected by the front surface is incident tothe CCD camera 310. Although the CCD camera 310 is sensitive to each ofthe IR rays and the visible light, the back-surface lighting device 250is in an off state and does not emit the IR rays. Thus, the CCD camera310 takes a front-surface image of the EC 32 that is formed by thevisible light. When the front surface of the EC 32 is lighted by thevisible light emitted by the ring lamp 320, the visible light is alsoincident to the back-surface lighting device 250 located in rear of theEC 32. However, since the block portion 220, the flange-like lightingportion. 254, and the auxiliary lighting portion 290 are covered by thedark IR-ray transmitting filters 240, 278, 300, almost all the visiblelight is absorbed by the filters 240, 278, 300, so that the CCD camera310 can take a light image of the EC 32 with a dark background that issuitable for image-data processing.

The control device 370 receives and processes image data representingthe silhouette or front-surface image of the EC 32 taken by the CCDcamera 310, or binary data converted from the image data. The controldevice 370 judges whether the EC 32 held by the suction pipe 192 is of acorrect sort to be mounted on the PCB 20, and determines the currentrotation position and current X-direction and Y-direction positions ofthe EC 32 held by the pipe 192. Then, the control device 370 comparesthe thus determined rotation position and X-direction and Y-directionpositions of the EC 32 with respective reference positions pre-stored inthe ROM 374, and calculates an angular error, 50, of the EC 32 about thecenter line thereof (i.e., the center axis line of the suction pipe 192)and X-direction and Y-direction positional errors, δX and δY, of thecenter of the EC 32. In the case where the CCD camera 310 takes thefront-surface image of the EC 32, the front-surface image may includeimages of characters and/or a bar code affixed to the front surface ofthe EC 32. In this case, the control device 370 analyses those imagesand identifies of what sort the EC 32 is.

While the control device 370 processes the image data or the binarydata, the EC 32 is transferred to the EC-mount position. Before the EC32 reaches the EC-mount position, the control device 370 finishes theprocessing of the data. Hence, the control device 370 operates therotation servomotor 84 to rotate the suction pipe 192 for removing theangular error δθ, and operates the X-Y robot 48 to move the EC holder 30to a modified EC-mount position which removes the X-direction andY-direction positional errors δX, δY. At the modified EC-mount position,the EC 32 held by the suction pipe 192 has a suitable rotation positionor phase and suitable X-direction and Y-direction positions, relative tothe PCB 20, for being mounted on the PCB 20. Then, the EC holder 30 islowered, the EC 32 held by the suction pipe 192 is pressed on apredetermined position on the PCB 20, and is fixed to the same 20 by,e.g., adhesion. Subsequently, the solenoid-operated direction-controlvalve 136 is switched to communicate the suction pipe 192 with theatmosphere and thereby cause the pipe 192 to release the EC 32. Then,the pipe 192 is elevated. Thus, the mounting of one EC 32 on the PCB 20ends. In the case where the control device 370 detects an excessivelybent lead wire of the EC 32, or judges that the EC 32 is not of the sortto be mounted, or in any other case where the control device 370 judgesthat the EC 32 should not be mounted on the PCB 20, the control device370 operates the X-Y robot 48 and the EC holder 30 to discard the EC 32into an EC-collect box (not shown), or takes other appropriate actions.The control device 370 may judge that the EC 32 is not of the sort to bemounted, e.g., if the EC 32 does not assume a posture with which the EC32 is to be mounted.

When the current suction nozzle 68 held by the holder body 70 of the ECholder 30 is not suitable for holding an EC 32 to be mounted, thecurrent nozzle 68 is exchanged with a suitable nozzle 68 stocked by thenozzle stocker 330. Midway in a movement to pick up the EC 32 from theEC supplying device 14, the EC holder 30 is stopped at a position abovethe nozzle stocker 330 to exchange the current nozzle 68 with a suitablenozzle 68. In the present embodiment, the current nozzle 68 held by theholder body 70 is returned to its exclusively corresponding holding hole340 of the nozzle stocker 330. However, the control device 370 may bemodified to return the current nozzle 68 to any one of the holding holes340 each of which can hold the same sort of nozzle 68 as that of the.current nozzle 68, or to any one of all the sorts of holding holes 340corresponding to all the sorts of nozzles 68, respectively.

The control device 370 stores, in the RAM 376 of the computer 380, dataindicating the sort of the current nozzle 68 held by the holder body 70,and data indicating the position of the holding hole 340 which had heldthe current nozzle 68 but now is empty. Based on those data, the controldevice 370 moves the holder body 70 to a position right above the empty,holding hole 340. At this timing, the the preventing-plate moving device360 has moved the preventing plate 334 to its retracted position on thenozzle stocker 330. In this state, the nozzle holding member 332 iselevated by an elevating and lowering device (not shown) and the holderbody 70 is lowered by the elevating and lowering device 62, so that thesuction pipe 192 of the current nozzle 68 fits into the empty holdinghole 340. An excessive downward movement of the holder body 70 isaccommodated by the compression of the compression coil spring 158.Subsequently, the preventing plate 334 is moved to its operativeposition so that one pair of preventing portions 354 are positionedabove the upper end surface of the block portion 220 and thereby preventthe nozzle 68 from coming off the holding hole 340. Then, the holderbody 70 is elevated toward its uppermost end position and, if the pairof preventing portions 354 apply, to the nozzle 68, a pulling-out forcegreater than the holding force applied thereto by the spring member 204,the fitting portion 194 of the nozzle 68 is removed from the receivinghole 196 of the adaptor 150, and the returning of the nozzle 68 to thenozzle stocker 330 ends.

After the holder body 70 thus returns the current nozzle 68 to thenozzle stocker 330, the X-Y robot 48 moves the holder body 70 to aposition above another nozzle 68 to be used next, as shown in FIG. 4.The holder body 70 is lowered, and the fitting portion 194 of the nextnozzle 68 fits into the receiving hole 196 of the adaptor 150, and isheld by the spring member 204. Subsequently, the preventing plate 334 ismoved to its retracted position and the holder body 70 is elevated totake out the next nozzle 68 from the nozzle stocker 330. Then, thepreventing plate 334 is moved to its operative position to prevent allthe nozzles 68 from coming off the nozzle holding member 332. Thus, theexchanging of suction nozzles 68 ends. Then, the EC holder 30 is movedto the EC supplying device 14 to take out the EC 32. As described above,the CCD camera 310 provided at the image-take position takes asilhouette or front-surface image of the EC 32. After the positional andangular errors of the EC 32 are corrected, the EC 32 is mounted on thePCB 20.

The current nozzle 68 held by the holder body 70 is exchanged withanother nozzle 68 when the current nozzle 68 turns to be defective as aresult of use. For example, in the case where the control device 370judges, based on the image taken by the CCD camera 310, that the currentnozzle 68 is not holding an EC 32 or is holding an EC 32 with anabnormal posture, or detects any other EC-holding error, the controldevice 370 records data indicating the fact, in the RAM 376 of thecomputer 380. If the detected EC-holding error meets a predeterminedcriterion or condition, the control device 370 judges that the currentnozzle 68 has a defect, such as bending, breakage, or excessive wearing,which leads to the occurrence of EC-holding error, and operates forexchanging the current nozzle 68 with another nozzle 68 as it does whenthe EC mounting system changes the current sort of ECs 32 to a differentsort of ECs 32 to be mounted next on the PCB 20.

As is apparent from the foregoing description, in the presentembodiment, the Y-direction slide 42, the EC holder 30, the elevatingand lowering device 62, the rotating device 64, the back-surfacelighting device 250, the ring lamp 320, etc. cooperate with one anotherto provide an EC holding apparatus as a sort of holding apparatus; andthe Y-direction slide 42 provides a support portion of the holdingapparatus. The suction pipe 192 provides a holding portion of theholding apparatus. The holder body 70 including the spline axis member72 and the adaptor 150 provides a support rod; the adaptor 150 and thespring member 204 cooperate with each other to provide an attachingdevice which attaches the suction nozzle 68 to the support rod; and theelevating and lowering device 62 provides a support-rod moving devicewhich advances and retracts the support rod in an axial directionthereof. The X-Y robot 48 provides a moving device which moves theholding apparatus; and the CCD camera 310 provides a common image takingdevice which functions as each of a first and a second image takingdevice. The block portion 220 of the suction-pipe holder 190 provides alight converting portion; and the reflecting surface 232 provides atapered reflecting surface. The light emitting diodes of the lightemitting bodies 258, 270, 294 provide light emitting elements as a sortof point light sources. The tubular lighting portion 252, theflange-like lighting portion 254, the auxiliary lighting portion 290,and the block portion 220 cooperate with one another to provide a lightemitting plate; and the light emitting surfaces 274, 290 of the lightemitting bodies 270, 294 and the lower surface 226 of the block portion220 cooperate with one another to provide a light emitting surface ofthe light emitting plate. The IR-ray transmitting filters 240, 278, 300also function as diffusing layers or plates.

In the present embodiment, the CCD camera 310 can takes either asilhouette or a front-surface image of each EC 32 depending upon, e.g.,the sort of each EC 32, by just selectively turning on the back-surfacelighting device 250 or the ring lamp 320. When the CCD camera 310 takesa silhouette image of an EC 32, the back-surface lighting device 250 isturned on to emit the IR rays to the back surface of the EC 32 held bythe suction pipe 192, so that the CCD camera 310 can take an excellentsilhouette image of the EC 32 with a sufficiently light background.Meanwhile, when the CCD camera 310 takes a front-surface image of an EC32, the IR-ray transmitting filters 240, 278, 300 of the back-surfacelighting device 250 function as a dark background of the EC 32, so thatthe CCD camera 310 can take a clear front-surface image of the EC 32.Since the back-surface lighting device 250 need not be moved away fromthe image-take position when the CCD camera 310 takes a front-surfaceimage, the present holding apparatus can enjoy a simple structure. Inaddition, since the CCD camera 310 is sensitive to both the IR rays andthe visible light, the EC transferring and mounting device 12 can enjoya simple construction, which contributes to reducing the production costthereof. Moreover, since the main portion 252, 254, 290 of theback-surface lighting device 250 are separate from the suction nozzle68, the main portion 252, 254, 290 remains on the holding apparatus,when the current nozzle 68 is exchanged with a different nozzle 6.8, andcan be used with the different nozzle 68. This feature contributes toreducing the overall cost needed to run the present EC mounting system.Furthermore, since the suction nozzle 68 can be advanced and retractedlightly, the ECs 32 can be quickly mounted on the PCB 20. In the presentembodiment, the elevating and lowering device 62 can be used commonlyfor moving the suction nozzle 68 to pick tip and mount the EC 32 and formoving the same 68 to exchange the current nozzle 68 with another nozzle68.

The elevating and lowering device 62 and the rotating device 64 employedin the present embodiment may be replaced with those, disclosed inJapanese Patent Application laid open for inspection purposes underPublication No. 8(1996)-78882, in which a spline axis member as asupport rod is connected to a ball screw such that the spline axismember is rotatable relative to the ball screw and is immovable relativeto the same in their axial direction, the spline axis member and theball screw are elevated and lowered as a unit by a Z-axis motor, and thespline axis member is rotated relative to the ball screw by a θ-axismotor. The support-rod moving device may be provided by afluid-pressure-operated cylinder device or any one of other knownsuitable devices. The point light sources may be provided by a lightemitting body including a number of optical fibers, or any one of otherknown suitable light sources. The common image taking device may beprovided by an array of imaging elements (i.e., “a line sensor”).

In the illustrated embodiment, the main portion 252, 254, 290 of theback-surface lighting device 250 and the ring lamp 320 as thefront-surface lighting device are attached to the Y-direction slide 42,and thus the Y-direction slide 42 functions as the support portion ofthe holding apparatus. However, the holder body 70 and the suctionnozzle 68 can be regarded as the holding apparatus and the holder body70 can be regarded as the support portion of the holding apparatus. Inthe latter case, the main portion 252, 254, 290 of the back-surfacelighting device 250 and at least a porton of the front-surface lightingdevice may be attached to the holder body 70. Alternatively, a member ordevice corresponding to the holder body 70 may be attached to a movablemember or a rotary plate, and the main portion 252, 254, 290 of theback-surface lighting device 250 and the at least porton of thefront-surface lighting device may be attached to one of the member ordevice corresponding to the holder body 70, the movable member, and therotary plate.

It is to be understood that the present invention may be embodied withvarious changes, improvements, and modifications that may occur to aperson skilled in the art without departing from the scope and spirit ofthe invention defined in the appended claims.

What is claimed is:
 1. A holding apparatus comprising: a suction nozzlewhich applies a negative pressure to a back surface of an object andthereby holds the object; a front-surface lighting device which emits afirst visible light toward a front surface of the object held by thesuction nozzle and thereby lights the front surface of the object sothat the first visible light forms an image of the front surface of theobject; and a back-surface lighting device which lights the back surfaceof the object held by the suction nozzle and which includes: (a) a lightemitting plate which is provided around a base portion of the suctionnozzle and emits a second light from a light emitting surface thereoffacing a vicinity of a free end of the suction nozzle that holds theobject; and (b) a black infrared-ray transmitting filter which coversthe light emitting surface of the light emitting plate, and transmitsinfrared rays of the second light so that the infrared rays light theback surface of the object and thereby forms a silhouette image of theobject, wherein when the front surface lighting device emits the firstvisible light toward the front surface of the object, the light emittingplate does not emit the second light, and the black infrared-raytransmitting filter does not transmit the infrared rays, and does notreflect the first visible light, thereby forming a black background ofthe image of the front surface of the object formed by the first visiblelight, and wherein when the light emitting plate emits the second light,and the black infrared ray transmitting filter transmits the infraredrays, thereby forming the silhouette image of the object, thefront-surface lighting device does not emit the first visible lighttoward the front surface of the object.
 2. A holding apparatus accordingto claim 1, wherein the light emitting plate comprises a plurality oflight emitting elements arranged along the light emitting surfacethereof, and a diffusing plate which covers the light emitting surfaceand which diffuses respective lights emitted by the light emittingelements and thereby emits a substantially uniform light.
 3. A holdingapparatus according to claim 1, further comprising a support portion towhich the suction nozzle is detachably attached, the back-surfacelighting device including a main portion which is separate from thesuction nozzle and is supported by the support portion such that whenthe suction nozzle is detached from the support portion, the mainportion remains supported by the support portion.
 4. A holding apparatusaccording to claim 3, wherein the main portion of the back-surfacelighting device comprises a tubular lighting portion which emits, froman inner surface thereof, a first light; and an outer lighting portionwhich extends outward from the tubular lighting portion and which emits,from one surface thereof, a second light in a direction parallel to acenterline of the tubular lighting portion, and wherein the suctionnozzle comprises a light converting portion which is fitable in an innerspace of the tubular lighting portion and which converts the first lightemitted by the tubular lighting portion into a third light having saiddirection parallel to the centerline of the tubular lighting portion;and a suction pipe which holds the object and which extends from one endof the light converting portion in said direction parallel to thecenterline of the tubular lighting portion, one end portion of thesuction nozzle that is opposite to the suction pipe being detachablyattached to the support portion.
 5. A holding apparatus according toclaim 4, wherein at least one of the tubular lighting portion and theouter lighting portion comprises a plurality of light emitting elementswhich emits respective lights and which are arranged on a plurality oflattice points, respectively; and a diffusing layer which diffuses thelights emitted by the light emitting elements and thereby emits asubstantially uniform light.
 6. A holding apparatus according to claim4, wherein the light converting portion comprises a tapered reflectingsurface which is coaxial with the suction pipe and whose radiusincreases in a direction away from a free end of the suction pipe thatholds the object.
 7. A holding apparatus according to claim 4, whereinthe light converting portion comprises a diffusing block which diffusesthe first light emitted by the tubular lighting portion and emits thethird light from an outer surface thereof located on a side of thesuction pipe.
 8. A holding apparatus according to claim 4, furthercomprising: a support rod which is supported by the support portion suchthat the support rod is movable in a direction parallel to an axis lineof the suction pipe; an attaching device which attaches the suctionnozzle to one end portion of the support rod such that the suctionnozzle is detachable from the support rod; and a support-rod movingdevice which moves the support rod in a direction parallel to an axisline thereof, thereby moving the light converting portion of the suctionnozzle relative to the tubular lighting portion in said directionparallel to the centerline thereof, so that the suction pipe of thesuction nozzle is advanceable and retractable in said direction parallelto the axis line thereof.
 9. A holding apparatus according to claim 4,wherein the main portion of the back-surface lighting device furthercomprises an auxiliary lighting portion which is opposed to a gapprovided between the tubular lighting portion and the light convertingportion and which emits a fourth light toward a side of the suction pipevia the gap.
 10. A transferring apparatus comprising: a holdingapparatus including: a suction nozzle which applies a negative pressureto a back surface of an object and thereby holds the object; afront-surface lighting device which emits a first visible light toward afront surface of the object held by the suction nozzle and therebylights the front surface of the object, so that the first visible lightforms an image of the front surface of the object; and a back-surfacelighting device which lights the back surface of the object held by thesuction nozzle and which includes: (a) a light emitting plate which isprovided around a base portion of the suction nozzle and emits a secondlight from a light emitting surface thereof facing a vicinity of a freeend of the suction nozzle that holds the object; and (b) a blackinfrared-ray transmitting filter which covers the light emitting surfaceof the light emitting plate, and transmits infrared rays of the secondlight so that the infrared rays light the back surface of the object andthereby forms a silhouette image of the object; wherein when thefront-surface lighting device emits the first visible light toward thefront surface of the object, the light emitting plate does not emit thesecond light, and the black infrared-ray transmitting filter does nottransmit the infrared rays, and does not reflect the first visiblelight, thereby forming a black background of the image of the frontsurface of the object formed by the first visible light, wherein w henthe light emitting plate emits the second light, and the blackinfrared-ray transmitting filter transmits the infrared rays, therebyforming the silhouette image of the object, the front-surface lightingdevice does not emit the first visible light toward the front surface ofthe object; a moving device which moves the suction nozzle and theback-surface lighting device of the holding apparatus in a directionperpendicular to an axis line of the suction nozzle; and at least oneimage taking device which is provided at at least one predeterminedposition in a range in which the moving device moves the suction nozzleand the back-surface lighting device of the holding apparatus, so thatwhen the suction nozzle and the back-surface lighting device arepositioned at the predetermined position, the image taking device isopposed to the suction nozzle and the back-surface lighting device andtakes at least one of (a) the silhouette image of the object held by thesuction nozzle and (b) the image of the front surface of the object withthe black background formed by the black infrared-ray transmittingfilter.
 11. A transferring apparatus according to claim 10, furthercomprising: a nozzle stocker which stocks at least one suction nozzle;and a nozzle-exchange control device which controls the moving device tomove the suction nozzle of the holding apparatus to a position where thesuction nozzle of the holding apparatus is opposed to the nozzlestocker, and causes the suction nozzle of the holding apparatus to beexchanged with the one suction nozzle stocked by the nozzle stocker. 12.A transferring apparatus according to claim 10, wherein the image takingdevice comprises a charge-coupled-device camera.
 13. An image takingsystem comprising: a front-surface lighting device which emits a firstvisible light toward a front surface of an object whose back surface isheld by a holding portion of a holding device and thereby lights thefront surface of the object, so that the first visible light forms animage of the front surface of the object; a first image taking devicewhich is sensitive to the first visible light and takes the image of thefront surface of the object being lighted by the front-surface lightingdevice; a back-surface lighting device which is provided in back of theobject held by the holding portion of the holding device, which lightsthe back surface of the object held by the holding portion, and whichincludes: (a) a light emitting plate which emits a second light from alight emitting surface thereof facing a vicinity of the holding portionholding the back surface of the object; and (b) a black infrared-raytransmitting filter which covers the light emitting surface of the lightemitting plate, and transmits infrared rays of the second light so thatthe infrared rays light the back surface of the object and thereby formsa silhouette image of the object, wherein when the front-surfacelighting device emits the first visible light toward the front surfaceof the object, the black infrared-ray transmitting filter does notreflect the first visible light and thereby forms a black background ofthe image of the front surface of the object formed by the first visiblelight; and a second image taking device which is sensitive to theinfrared rays and takes the silhouette image of the object being lightedby the back-surface lighting device, wherein the second image takingdevice is provided, on a plane substantially parallel to the front andback surfaces of the object held by the holding portion of the holdingdevice, at a position different from a position where the first imagetaking device is provided.
 14. An image taking system, comprising: afront-surface lighting device which emits a first visible light toward afront surface of an object whose back surface is held by a holdingportion of a holding device and thereby lights the front surface of theobject, so that the first visible light forms an image of the frontsurface of the object; an image taking device which is sensitive to thefirst visible light and takes the image of the front surface of theobject being lighted by the front-surface lighting device; and aback-surface lighting device which is provided in back of the objectheld by the holding portion of the holding device, which lights the backsurface of the object held by the holding portion, and which includes(a) a light emitting plate which emits a second light from a lightemitting surface thereof facing a vicinity of the holding portionholding the back surface of the object; and (b) a black infrared-raytransmitting filter which covers the light emitting surface of the lightemitting plate, and transmits infrared rays of the second light so thatthe infrared rays light the back surface of the object and thereby formsa silhouette image of the object, wherein when the front-surfacelighting device emits the first visible light toward the front surfaceof the object, the light emitting plate does not emit the second light,and the black infrared-ray transmitting filter does not transmit theinfrared rays, and does not reflect the first visible light, therebyforming a black background of the image of the front surface of theobject formed by the first visible light, wherein when the lightemitting plate emits the second light, and the black infrared-raytransmitting filter transmits the infrared rays, thereby forming thesilhouette image of the object, the front-surface lighting device doesnot emit the first visible light toward the front surface of the object,and wherein the image taking device is sensitive to the infrared raysand takes the silhouette image of the object being lighted by theback-surface lighting device.
 15. An image taking system according toclaim 14, wherein the image taking device comprises acharge-coupled-device camera.
 16. A method of taking an image of anobject which is held by a holding device, comprising the steps ofproviding, in front of the object whose back surface is held by aholding portion of the holding device, a front-surface lighting devicewhich emits a first visible light toward a front surface of the objectand thereby lights the front surface of the object, so that the firstvisible light forms an image of the front surface of the object,providing, in back of the object held by the holding portion of theholding device, a back-surface lighting device which lights the backsurface of the object held by the holding portion and which includes:(a) a light emitting plate which emits a second light from a lightemitting surface thereof facing a vicinity of the holding portionholding the back surface of the object; and (b) a black infrared-raytransmitting filter which covers the light emitting surface of the lightemitting plate, and transmits infrared rays of the second light so thatthe infrared rays light the back surface of the object and thereby formsa silhouette image of the object, wherein when the front-surfacelighting device emits the first visible light toward the front surfaceof the object, the black infrared-ray transmitting filter does notreflect the first visible light and thereby forms a black background ofthe image of the front surface of the object formed by the first visiblelight, operating the front-surface light device and a first image takingdevice which is sensitive to the first visible light, to take, in theblack background formed by the black infrared-ray transmitting filter,the image of the front surface of the object that is lighted by thefront-surface lighting device; and operating the back-surface lightingdevice and a second image taking device which is sensitive to theinfrared rays of the second light and is provided, on a planesubstantially parallel to the front and back surfaces of the object heldby the holding portion of the holding device, at a position differentfrom a position where the first image taking device is provided, to takethe silhouette image of the object whose back surface is lighted by theback-surface lighting device.
 17. A method of taking an image of anobject which is held by a holding device, comprising the steps of:providing, in front of the object whose back surface is held by aholding portion of the holding device, a front-surface lighting devicewhich emits a first visible light toward a front surface of the objectand thereby lights the front surface of the object, so that the firstvisible light forms an image of the front surface of the object,providing, in back of the object held by the holding portion of theholding device, a back-surface lighting device which lights the backsurface of the object held by the holding portion and which includes:(a) a light emitting plate which emits a second light from a lightemitting surface thereof facing a vicinity of the holding portionholding the back surface of the object; and (b) a black infrared-raytransmitting filter which covers the light emitting surface of the lightemitting late, and transmits infrared rays of the second light so thatthe infrared rays light the back surface of the object and thereby formsa silhouette image of the object, wherein when the front-surfacelighting device emits the first visible light toward the front surfaceof the object, the light emitting plate does not emit the second light,and the black infrared-ray transmitting filter does not transmit theinfrared rays, and does not reflect the first visible light, therebyforming a black background of the image of the front surface of theobject formed by the first visible light, wherein when the lightemitting plate emits the second light, and the black infrared-raytransmitting filter transmits the infrared rays, thereby forming thesilhouette image of the object, the front-surface lighting device doesnot emit the first visible light toward the front surface of the object,operating the front-surface lighting device and an image taking devicewhich is sensitive to the first visible light, to take, in the blackbackground formed by the black infrared-ray transmitting filter, theimage of the front surface of the object that is lighted by thefront-surface lighting device, and operating the back-surface lightingdevice and the image taking device which is sensitive to the infraredrays of the second light, to take the silhouette image of the objectwhose back surface is lighted by the back-surface lighting device.